HH's point is an interesting one. Several good reasons have been given why many original specs were like they were and I cannot see a manufacturer deliberately exceeding the required spec as this would create problems with other aspects of the design.
The Harrier GR1 spec of the mid 60s was interesting in that it called for a 2000nm unrefuelled ferry range (rather more than the range of Trident airliners of the day). We met the spec by unscrewing the small wing tips that were outboard of the outrigger wheeels and replacing them with slightly larger so called 'ferry tips'. This took about 45 minutes but I don't ever recall the RAF using this capability.
When I wandered about in the Dunsfold demonstrator G-VTOL (particularly all over South America for example) we were always airborne on our own and often unable to contact our destination until well on the way. So I never planned a leg longer that 1000-1200 miles to keep stacks in hand for whatever. On occasion this caused real aggro at our destination as I always refused to demo on arrival having so much fuel and a congfiguration that reduced the max g . This did not go down well with Generals and salesmen alike.
Hey ho.